The present invention pertains to improved methods of insert molding a film laminate, or the like, over a portion of a plastic substrate and to the parts made thereby.
A variety of film laminate injection molded parts have been made and used for automobile body and trim parts. For example, bumpers, body panels, doors, filler panels, wheel covers, dashboards, armrests and other parts have been made via injection molding techniques. Additionally, with regard to automobile exteriors, bodyside trim moldings, beltline moldings, roof moldings and window moldings are made via injection molding of polyvinylchloride (PVC) or other thermoplastic materials.
In order to provide a painted surface for these parts, film lamination techniques are commonly employed. In accordance with these processes, a paint film laminate is insert molded with the desired thermoplastic to fuse the film laminate over the injection molded part. The resulting injection molded part is ready for assembly without subsequent painting.
The paint film laminate used in these insert molding techniques may comprise a backing sheet to which paint layers are adhered to form a colored side of the laminate. Typically, the backing sheet comprises an extruded thermoplastic sheet. In such paint film laminates, a paint film, comprising a cast dried continuous paint coating, is provided over the backing sheet. The paint film laminate may consist of a monocoat, a clear coat over a base coat, or a clear coat and a base coat with interposed print or design. The paint film laminate, including base coat, clear coat and print or design, if desired, may, for example, range from about 0.5-4 mil. in thickness.
The laminated paint films are typically provided in a roll, unwound, then trimmed to a proper xe2x80x9cpreformxe2x80x9d size and shape, ready for insertion into the injection mold. The preform is usually placed along the cavity side of the mold with the painted side thereof facing the mold cavity surface.
In some instances, the pre-sized paint film laminate may be placed along the core side of the mold. The mold is then clamped and the desired molten resin is injected into the mold cavity. Heat and pressure conditions in the mold partially melt the backing sheet and a melt bonding or fusion of the injected resin and film laminate occur. Injection molds used for these processes are commonly rear or edge gated so that the molten resin is directed along the backside of the film laminate, pressing the show face side of the film laminate against the surface of the mold cavity. Techniques utilized to insert mold plastic parts covered by such paint film laminates are disclosed, for example, in U.S. Pat. Nos. 5,599,608; 5,783,287; 5,746,962 and 6,168,742 of common assignment herewith. The subject matter of these disclosures is incorporated by reference herein.
It has become increasingly popular to insert or co-mold bumper, rocker panel, side trim, and chin spoiler parts for autos and trucks which incorporate a paint film laminate over only a portion of the show surface of the part with the remainder of the underlying plastic substrate being exposed so as to present a plural color or plural component show surface appearance.
Conventionally employed insert molding techniques for manufacturing such plural colored film laminate parts often result in an unsightly appearance wherein the border between the paint film and the exposed substrate presents an uneven or wavy appearance on the show surface that stands in sharp contrast to the desired straight line or clean edge appearance that is intended and which must be achieved if the part is to be classified as a Class xe2x80x9cAxe2x80x9d show part. This undesirable appearance may be caused, for example, by shrinkage of the paint film laminate during the insert molding process.
Accordingly, there remains a need in the art to improve upon the existing methods for insert molding of film laminates over plastic substrates in such manner that the border area of the laminate that is disposed on the show face of the part provides for a sharp, linear distinction between the film laminate surface and the exposed substrate surface.
These and other objects of the invention are met by the instant methods and fused film laminate plastic parts made thereby.
In accordance with the present invention, a film laminate part is insert molded utilizing a specifically configured mold cavity. The method includes the steps of providing a film laminate and subsequently insert molding a plastic substrate against the non-show-face side of the preformed film laminate. A film laminate preforming step may be used and involves shaping an unformed film laminate in a specially configured vacuum mold and subsequently trimming the shaped film laminate to obtain the preformed film laminate, with insert or edge portions, to be insert molded. The insert molding step involves positioning the preformed film laminate in a specially configured mold cavity such that the insert or edge portion thereof, to be disposed on the show face, is located adjacent a groove forming member within the mold cavity, closing the mold and injecting molten thermoplastic or thermosetting resin into the mold cavity against the non-show face side of the film laminate.
Improvement in traditional insert molding techniques is provided by utilization of a specific mold cavity structure with a ridge-like groove forming member(s) therein which facilitates disposition of each paint film laminate insert or edge portion to be disposed on the show face of the part, within a separate groove which extends along the show face side of the resulting part. The mold cavity is equipped with a groove forming member(s) which align with the insert or edge portion(s) of the paint film laminate to be disposed on the show face of this part. Each groove forming member is configured with a predetermined depth to width ratio which results in the film laminate edges being disposed within the groove(s) such that the viewer will see only the film laminate at the point where it crests the entrance to the resulting groove and not the actual edge line located near the nadir of the groove.
In one embodiment of the present invention, the film laminate covers at least one edge of the underlying substrate. In this case, the film laminate may be preformed with a reentrant longitudinal edge portion, in accordance with the ""287 patent to Yamamoto and the like, such that the re-entrant longitudinal edge portion of the film laminate covers the associated longitudinal edge of the plastic substrate.
The invention will be further described in conjunction with the appended drawings and following detailed description.